Not just kaneki. Majority characters were wasted. I couldn't understand anything in season 3. Randomly new characters kept on poping.
Yep, it's because Shitrrot cut lots of content and the 2nd season basically went a different route, which was terribly written, than the original manga. Ishida was even thankful enough to send them a detailled script about this alternative route; they legit skipped 90% of all that stuff.
Characters like Tsukiyama, Amon, Takizawa, Eto, etc. were handled so much better in the manga, including several other characters. They cut even lots of stuff in the 1st season - a lot of interactions between Touka and Kaneki. In the first place, Kaneki never joined Aogiri after demolishing Yamori. And Ayato also didn't just have a "short clash" against Kaneki either.
Even when it comes to the abilities, Kagune, Kakuja, etc, the manga explained it so much better.
Also, the Q squad is based on investigators with ghoul abilities (the group in the 3rd season who were the MCs with Sasaki). The reason why their abilities were somewhat limited compared to ghouls is the fact that their RC Cells are restricted on purpose. Idk if the anime even explained this step.
See, that's just a few stuff which I remember and all that information is already crucial for your judgement when it comes to the anime because this information is simply missing. Now, don't worry, this stuff isn't highly huge spoiler, it's just a bunch of information to understand certain or a lot of abilities better.